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How do I perform an IF…THEN in an SQL SELECT?
How do I perform an IF...THEN in an SQL SELECT statement?
30 Answers
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MySQL ON vs USING?
...n tables ON a column, a set of columns and even a condition. For example:
SELECT * FROM world.City JOIN world.Country ON (City.CountryCode = Country.Code) WHERE ...
USING is useful when both tables share a column of the exact same name on which they join. In this case, one may say:
SELECT ... FR...
How to concatenate text from multiple rows into a single text string in SQL server?
...y, John, Sam
2 Alaina, Edward
I used the following T-SQL:
SELECT Main.SubjectID,
LEFT(Main.Students,Len(Main.Students)-1) As "Students"
FROM
(
SELECT DISTINCT ST2.SubjectID,
(
SELECT ST1.StudentName + ',' AS [text()]
FR...
How to submit form on change of dropdown list?
I am creating a page in JSP where I have a dropdown list and once the user selects a value he has to click on the go button and then the value is sent to the Servlet.
...
How can I select rows with most recent timestamp for each key value?
...r data. Each row has a sensor id, a timestamp, and other fields. I want to select a single row with latest timestamp for each sensor, including some of the other fields.
...
Validate that a string is a positive integer
... but if that results in a blank string, restores a single 0.
Number(str): Convert str to a number; the number may well have a fractional portion, or may be NaN.
Math.floor: Truncate the number (chops off any fractional portion).
String(...): Converts the result back into a normal decimal string. Fo...
parseInt vs unary plus, when to use which?
...
The unary + on the other hand will return NaN if the entire string is non-convertible to a number.
parseInt('2a',10) === 2; //true
parseFloat('2a') === 2; //true
isNaN(+'2a'); //true
As seen in the comment of @Alex K., parseInt and parseFloat will parse by character. This means ...
How do you round a number to two decimal places in C#?
...per to specify the type of rounding (Round-to-even or Away-from-zero). The Convert.ToInt32() method and its variations use round-to-even. The Ceiling() and Floor() methods are related.
You can round with custom numeric formatting as well.
Note that Decimal.Round() uses a different method than Mat...
Assigning variables with dynamic names in Java
...
Excellent when you need to convert Android's sensor event.values[] into a set of variables. event.values[] could have a length from 1 to 6 and it's handy to have it convert, in my case for an array-less json marshaling.
– Farshid ...
How can I select the first day of a month in SQL?
I just need to select the first day of the month of a given datetime variable.
30 Answers
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